Most recent releases including the current one were (iirc) phgc34 - ph59 - phgc33 - ph60 - phgc32. So, alternating gc - non-gc, and gc in decreasing order, non-gc in increasing order. If that continues, the next releases would ph61 - phgc31 - ph62 - phgc30 and so on.
I think there were "schemes"...